a. Field of the Invention:
This invention relates to a novel preparation process of 4-(4-hydroxyphenyl)-cyclohexanol, which is a compound usual as a monomer for liquid crystalline polyesters and the like.
b. Description of the Prior Art:
As processes for the synthesis of 4-(4-hydroxy-phenyl)-cyclohexanol, there have been proposed the following three processes only.
(1) After monomethylation of 4,4'-biphenol, hydrogenation is effected to obtain 4-(4-methoxyphenyl)-cyclohexanone. It is then oxidized into 4-(4-methoxyphenyl)-cyclohexanone with a chromium compound, followed by demethylation with aluminum bromide so as to synthesize 4-(4-hydroxyphenyl)-cyclohexanone. It is thereafter reduced with sodium boron hydride. [Chem. & Ind., 1437 (1958)].
(2) 4,4'-Biphenol is reacted with hydrogen in the presence of a Raney-nickel catalyst, thereby synthesizing 4-(4-hydroxyphenyl)-cyclohexanol [J. Am. Chem Soc., 76, 1733 (1954)].
(3) 4-(4-Tosyloxycyclohexyl)-phenol is subjected to decomposition in the presence of a potassium tert.butoxide catalyst [Chem. & Ind., 1437 (1958)].
The above-described conventional processes are accompanied by drawbacks such as many steps are required, the yield is low and expensive raw materials are required, so that the resultant 4-(4-hydroxyphenyl)-cyclohexanol naturally and unavoidably becomes extremely expensive. The above-described conventional processes are hence by no means satisfactory.